Microbiological organisms are frequently used as food supplements. One example are probiotic bacteria which are known to have beneficial effects on the intestinal microflora increasing the resistance to infectious disease such as diarrhea. Probiotics have also been shown to be involved in the modification of blood chemistry and in immunomodulation (see references listed under Potential Health Benefits in the reference section).
Probiotic bacteria can be found in dairy products such as yogurt and species known to have health benefits include those from the genera Enterococcus and Lactobacillus. However, probiotic dairy products have a short shelf life. Probiotics are also available to the consumer in form of powder or tablets. A further application of probiotics relates to use in animal feed.
Current methods for storing bacterial cultures typically use lyophilization, also called freeze-drying. In this process, water is removed from the organism by sublimation and the organism and can be revived after the addition of water. However, freeze-dried bacteria are not metabolically active and it is well known that freeze-dried products typically lose much of their resilience after a few weeks of storage at room temperature (Fonseca et al and Murga et al).
Furthermore, many commercial probiotics do not seem to contain all of the species mentioned on the labels, and where bacteria are present the numbers of viable bacteria are often very low (J. Hamilton-Miller).
The present inventors have now determined that stable preparations of viable, metabolically active bacteria can be prepared by use of a particular growth substrate which contains balanced amounts of complex and simple carbohydrates. In contrast to prior art probiotics, the preparations provided according to the present invention comprise high numbers of stable and active bacteria which can be maintained during long term storage.